1. Field of Invention
This invention relates generally to a stabilizer system for cabinet or rack-mounted sensitive equipment which serves effectively to isolate the unit from shock and vibratory forces, and more particularly to a system which is self-stabilizing and therefore need not be affixed to the structure adjacent to the foundation on which the cabinet or rack is installed.
2. Status of Prior Art
When sensitive equipment such as electronic systems, communication units, digital computers and delicate machines are installed and operated in an environment which subjects the equipment to shock and vibratory forces, these forces may impair the equipment or interfere with its proper functioning. It is, therefore, necessary to so mount the equipment as the effectively isolate it from these adverse forces.
Thus in U.S. Pat. No. 804,884 to Rutan, a machine to be protected is mounted on a chassis that floats within a frame. This is achieved by vertical springs interposed between the underside and upperside of the chassis and the base wall and top wall of the frame, respectively, and by lateral springs interposed between opposite edges of the chassis and the corresponding side walls of the frame. The floating machine is thereby effectively isolated from the shock and vibratory forces to which the frame is subjected.
The Bennett U.S. Pat. No. 2,145,037 shows a radio cabinet having at each of its corners a cylindrical duct in which is received a spring-loaded cushion that rests on a floor subjected to shock forces, thereby isolating the radio from these forces.
In the Meyerle U.S. Pat. No. 4,251,045, a turntable chassis is supported by springs within a cabinet that rests on a platform supported above ground by resilient pads. The Scotto U.S. Pat. No. 3,459,395 discloses shock-sensitive equipment mounted on a platform having four shock absorbers at its corners supporting the platform within the hull of boat.
Thus the use of springs and resilient pads is a common expedient for the protection of sensitive equipment from shock and vibratory forces.
The concern of the present invention is with the requirements imposed by Army, Navy and Air Force agencies for protecting rack or cabinet-mounted electronic equipment, computer system and communication units against shock and vibratory forces. These requirements are more stringent than those imposed on equipment which is installed in environments which experience lesser shock and vibratory forces, for in military environments one can encounter intense forces.
The protection of a unit within itself or between the unit and the rack or cabinet in which it is mounted is usually inadequate when the shock and vibratory forces to which the unit is subjected are intense. It is therefore the common practice to mount the whole rack or cabinet on resilient elements that absorb or attenuate these forces. Attenuation or dampening of shock and vibratory forces is obtained by deflection of the resilient elements which acts to absorb the forces to then release them over a longer period of time and thereby isolate the unit from the forces.
However, when the cabinet or rack in which the sensitive equipment is housed is tall, then stabilizers are needed, otherwise the excursion of the rack at its top due to rotational motion would be excessive and unacceptable. The conventional technique for effecting such stabilization is to have a set of mounts at the top or toward the top of the rack or cabinet.
The drawback to this mode of stabilization is that one then needs to affix the stabilizer mounts to the existing superstructure which in a shipboard installation is decking or a bulkhead. In some instances there is no place close enough to which the stabilizer mounts can be connected. In other cases, the cost of adjusting or modifying the structure to render it suitable for affixing stabilizer mounts thereto may be prohibitive.
As used herein, the term rack is to be understood to mean not only a framework on which sensitive equipment is mounted, but also a console, a cabinet or any other housing containing the equipment. And the term shock forces, as used herein, is to be understood to mean not only sudden impact forces, but also sutained vibratory forces.
When therefore a rack is shock-mounted it is protected against whatever forces seek to shock the sensitive equipment housed in the rack.